(i) Field of the Invention
The present invention relates to a carbon microsensor electrode usable as, for example, an electrochemical detector, an environmental analysis sensor, a pathologic inspection sensor, and a probe electrode which is for the detection of an organism, a food and the like, and which is severely required to be harmless and non-toxic.
(ii) Description of the Prior Art
A rapid analysis using a sensor as a detecting tools which has been promptly developed in recent years in the wide field of an electrochemical determination has a very high selectivity and permits a high-sensitive measurement, and for this reason, this kind of rapid analysis begins to be often used in the analysis and evaluation of clinical samples and environmental samples each containing a trace amount of a component to be analyzed and many other kinds of compounds.
Recently, it has got very important to obtain biological information in vivo and in situ in a local site of an organism, for example, in a cell by the use of a sensor electrode capable of detecting such a specific material with a high sensitivity.
For this purpose, it is required that the electrode is set in the close vicinity of a target cell of the organism or thrust into the cell to give a physical, chemical or electrical irritation to the cell, so that a response material is released or a specific material is chemically produced, and the resultant material is detected and determined on the electrode.
Heretofore, as examples of such an electrode for determination, there have been developed a pH meter for measuring hydrogen ions, an ion sensor for detecting inorganic ions such as sodium ions, a sensor prepared by chemically modifying the surface of a carbon fiber (CF) or glass-like carbon (GC) with a complex or an organic material, various enzyme sensors such as a glucose sensor prepared by mixing a paste of a carbon paste (CP) electrode with an enzyme such as glucose oxidase and then coating the mixture with an ion permeable membrane, a biosensor having an immune metabolite and the like.
However, the chemically modified sensor, the enzyme sensor and the biosensor cannot withstand a long-term use except the pH meter and the inorganic ion sensor. That is, they have the drawback that their life is short.
In particular, most of the sensors in which the only surface of each electrode is chemically modified can scarcely withstand practical use.